478 ORGANOLOGY. 



Let us suppose tins would yield 6 per cent, of organic substance, which 

 is the outside of the fact. The old Hessian acre (Morgen) (40,000 n F.) 

 bears, according to Block, at least 1710 Ibs. of straw and 500 Ibs. of grain. 

 I will put it down at only 1076 Ibs. of organic substance for the two. 

 The depth of soil may be taken at 12 inches, the cubic foot 2*0 P. sp. ; 

 thus each Morgen, through cultivation, would yield 57,600 Ibs., which, 

 according to the above calculation, would suffice for a culture of 500 

 years. But mould, according to Saussure, loses, through putrefaction, at 

 least 5 per cent., so that, according to the above calculation of its quantity 

 (6 per cent.), in the first year it would lose 14,400 Ibs., so that the 57,600 

 Ibs. would not supply 10 years' consumption. This analysis of Herrmann 

 must be allowed to be very bad. .With the clay he finds no trace of alkali, 

 although the soil had grown wheat for centuries, and no phosphoric acid, 

 except 0'46 per cent, of phosphate of iron and alumina. A better analysis 

 of this highly interesting soil is wanted. That these calculations, however, 

 may, on the whole, be relied on is proved by other cases. The arable 

 land of the Saalaue at Jena contains nearly one per cent, of humic acid 

 combined with ammonia, and is a very beautiful wheat soil. The specific 

 gravity is 2-59, so that the top soil, 12" deep, of a single old Hessian 

 Morgen of 40,000 n ' weighs 6,800,000 Ibs., and consequently contains 

 about 68,000 Ibs. of humus. According to Boussingault, a soil in an average 

 state of culture delivers 1050 Ibs. per Morgen more organic matters 

 than it receives through manures, so that these fields must be exhausted 

 in 70 years, and, if the putrefaction is reckoned, in 25 years. But this 

 arable land lias been formed within the last century by the breaking up 

 of meadow land, some of which still remains and is remarkable for its 

 growth of grass ; the average of six analyses of this meadow land gives 

 0*49 per cent, of humus, or about half of that of the arable land. 



One of the most striking facts demanding an explanation of the 

 defenders of the organic theory of vegetable nutrition is the agriculture 

 of the Alps. No one thinks of manuring these alpine pastures ; countless 

 herds are nourished in the summer upon its grass and herbs, and return 

 at the utmost in their excrements but half of the organic substance they 

 take up. Large quantities of cheese are annually conveyed away from 

 these pastures, with no return but thanks ; hay is also taken from them 

 and converted into dollars. This system has been carried on in the 

 Alps for centuries, in some places for a thousand years, and yet no one 

 has observed any deficiency in the fruitfulness of these regions. Can 

 any one be so foolish as to maintain that the thin covering of soil which 

 often lies upon the naked rocks is so rich in organic substances as to 

 furnish this constant loss without exhibiting any remarkable change ? 



Lastly, we can make a calculation for the cultivation of land for an 

 indefinite period. According to Boussingault, a Morgen of well-culti- 

 vated soil on an average yields 2480 Ibs. of dry organic substance, and 

 receives in manure only 795 Ibs., or not more than a third part.* Every 

 well-cultivated soil, instead of being the poorer in humus from the loss 

 of organic substance and the attendant putrefaction, is the richer. It is 

 not, however, necessary to refer to the investigations of Boussingault, as 

 any one may be convinced of the absurdity of the humus-theorists by 



* An objection might be urged here, that the ammonia is lost in the drying of the 

 manure ; but I have only taken into consideration the dry organic substance of the 

 manure. 



